Back to EveryPatent.com
United States Patent |
5,305,616
|
Coffinberry
|
April 26, 1994
|
Gas turbine engine cooling system
Abstract
A gas turbine engine cooling system. A first turbocompressor and a heat
exchanger are fluidly interconnected and are each in fluid communication
to receive air of differing pressures and temperatures. Typically, such
air is received from various regions of the engine low pressure compressor
and the engine high pressure compressor. The system delivers air through a
duct to a portion of the engine for cooling, such as the engine high
pressure turbine region, at lower temperatures and higher pressures than
if cooling air were directly ducted from the engine compressor to the
engine turbine.
Inventors:
|
Coffinberry; George A. (West Chester, OH)
|
Assignee:
|
General Electric Company (Cincinnati, OH)
|
Appl. No.:
|
856318 |
Filed:
|
March 23, 1992 |
Current U.S. Class: |
62/402; 60/784; 62/87 |
Intern'l Class: |
F25D 009/00 |
Field of Search: |
62/87,402
|
References Cited
U.S. Patent Documents
4461154 | Jul., 1984 | Allam | 62/402.
|
4539816 | Sep., 1985 | Fox | 62/402.
|
5036678 | Aug., 1991 | Renninger et al. | 62/402.
|
5056335 | Oct., 1991 | Renninger et al. | 62/402.
|
Primary Examiner: Capossela; Ronald C.
Attorney, Agent or Firm: Erickson; Douglas E., Squillaro; Jerome C.
Claims
I claim:
1. A system for cooling a first portion of a gas turbine engine, said
engine having an engine compressor, and said cooling system comprising:
(a) a turbocompressor having a compressor section and a turbine section
each with an inlet and an outlet; and
(b) a first heat exchanger having an inlet and an outlet for a first fluid
flow providing cooling to said first heat exchanger and having an inlet
and an outlet for a second airflow receiving cooling from said first heat
exchanger, said first fluid flow inlet of said first heat exchanger in
fluid communication with lower temperature fluid, said second airflow
inlet of said first heat exchanger in fluid communication with higher
temperature air from said engine compressor, said second airflow outlet of
said first heat exchanger in fluid communication with said inlet of said
compressor section of said turbocompressor, and said outlet of said
compressor section of said turbocompressor in fluid communication with
said first portion of said engine for said cooling of said first portion
of said engine and wherein said higher temperature air has a higher
temperature than that of said lower temperature fluid.
2. The cooling system of claim 1, wherein said first fluid flow is a first
airflow, said first fluid flow inlet is a first airflow inlet, said first
fluid flow outlet is a first airflow outlet, said lower temperature fluid
is lower temperature air, and said higher temperature air has a higher
pressure and temperature than that of said lower temperature air.
3. The cooling system of claim 2, wherein said engine includes a fan bypass
duct and said first airflow outlet of said first heat exchanger is in
fluid communication with said fan bypass duct.
4. The cooling system of claim 2, wherein said engine compressor includes a
high pressure compressor and said higher pressure and temperature air
includes a portion of discharge air from said high pressure compressor.
5. The cooling system of claim 2, wherein said inlet of said turbine
section of said turbocompressor is in fluid communication with
intermediate pressure and temperature air from said engine compressor,
wherein said intermediate pressure and temperature air having a pressure
and temperature intermediate that of said lower pressure and temperature
air and said higher pressure and temperature air.
6. The cooling system of claim 5, also including a second heat exchanger
having an inlet and an outlet for a third airflow providing cooling to
said second heat exchanger and having an inlet and an outlet for a fourth
airflow receiving cooling from said second heat exchanger, said third
airflow inlet of said second heat exchanger in communication with air
having a pressure and temperature lower than that of said intermediate
pressure and temperature air, said fourth airflow inlet of said second
heat exchanger in communication with said outlet of said turbine section
of said turbocompressor, and said fourth airflow outlet of said second
heat exchanger in communication with a second portion of said engine for
cooling of said second portion of said engine.
7. The cooling system of claim 6, wherein said engine includes a fan duct
and said third airflow outlet of said second heat exchanger is in fluid
communication with said engine fan duct.
8. The cooling system of claim 6, wherein said engine compressor includes a
high pressure compressor and said higher pressure and temperature air
includes a portion of discharge air from said high pressure compressor.
9. The cooling system of claim 6, wherein said engine includes a booster
compressor, said lower pressure and temperature air includes a portion of
discharge air from said booster compressor, and said bleed air in
communication with said third airflow inlet of said second heat exchanger
having generally the same pressure and temperature as that of said lower
pressure and temperature air.
10. A system for cooling a first portion of a gas turbine engine, said
engine having an engine compressor, and said cooling system comprising:
(a) a turbocompressor having a compressor section and a turbine section
each with an inlet and an outlet; and
(b) a first heat exchanger having an inlet and an outlet for a first fluid
flow providing cooling to said first heat exchanger and having an inlet
and an outlet for a second airflow receiving cooling from said first heat
exchanger, said first fluid flow inlet of said first heat exchanger in
fluid communication with lower temperature fluid, said second airflow
inlet of said first heat exchanger in fluid communication with said outlet
of said compressor section of said turbocompressor, said inlet of said
compressor section of said turbocompressor in fluid communication with
higher temperature air from said engine compressor and said second airflow
outlet of said first heat exchanger in fluid communication with said first
portion of said engine for said cooling of said first portion of said
engine and wherein said higher temperature air has a higher temperature
than that of said lower temperature fluid.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to gas turbine engines, and more
particularly to a system for cooling such an engine.
Gas turbine engines (such as turbojet engines, bypass turbofan engines,
turboprop engines, turboshaft engines, etc.) may be used to power flight
vehicles (such as planes, helicopters, and missiles, etc.) and may also be
used to power ships, tanks, electric power generators, pipeline pumping
apparatus, etc. For purposes of illustration, the invention will be
described with respect to an aircraft bypass turbofan gas turbine engine.
However, it is understood that the invention is equally applicable to
other types and/or uses of gas turbine engines.
A gas turbine engine includes a core engine having, in serial flow
relationship, high pressure compressor (also called a core compressor) to
compress the airflow entering the core engine, a combustor in which a
mixture of fuel and the compressed air is burned to generate a propulsive
gas flow, and a high pressure turbine which is rotated by the propulsive
gas flow and which is connected by a larger diameter shaft to drive the
high pressure compressor. A typical aircraft bypass turbofan gas turbine
engine adds a low pressure turbine (located aft of the high pressure
turbine) which is connected by a smaller diameter coaxial shaft to drive a
front fan (located forward of the high pressure compressor) which is
surrounded by a nacelle and which may also drive a low pressure compressor
(located between the front fan and the high pressure compressor). The low
pressure compressor sometimes is called a booster compressor or simply a
booster. It is understood that the term "compressor" includes, without
limitation, high pressure compressors and low pressure compressors. A flow
splitter, located between the fan and the first (usually the low pressure)
compressor, separates the air which exits the fan into a core engine
airflow and a surrounding bypass airflow. The bypass airflow from the fan
exits the fan bypass duct to provide most of the engine thrust for the
aircraft. Some of the engine thrust comes from the core engine airflow
after it flows through the low and high pressure compressors to the
combustor and is expanded through the high and low pressure turbines and
accelerated out of the exhaust nozzle.
Aircraft bypass turbofan gas turbine engines are designed to operate at
high temperatures to maximize engine thrust. Cooling of engine hot section
components (such as the combustor, the high pressure turbine, the low
pressure turbine, and the like) is necessary because of the thermal
"redline" limitations of the materials used in the construction of such
components. Typically such cooling of a portion of the engine is
accomplished by ducting (also called "bleeding") cooler air from the high
and/or low pressure compressors to those engine components which require
such cooling. Unfortunately the relatively low pressure and hot
temperature of the compressor air limits its ability to be used to cool
such engine components.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a system for improved cooling
of the hot section components and other portions of a gas turbine engine.
In a first embodiment, the invention provides a system for cooling a
portion of a gas turbine engine and includes a turbocompressor and a first
heat exchanger. The first heat exchanger has an inlet and an outlet for a
first fluid flow providing cooling to the first heat exchanger and has an
inlet and an outlet for a second airflow receiving cooling from the first
heat exchanger. The first fluid flow inlet is in fluid communication with
lower temperature fluid (e.g., lower pressure and temperature discharge
air from the booster compressor section of the engine compressor). The
second airflow inlet is in fluid communication with higher temperature air
from the engine compressor (e.g., higher pressure and temperature
discharge air from the high pressure compressor section of the engine
compressor). The second airflow outlet is in fluid communication with the
inlet of the compressor section of the turbocompressor. The outlet of the
compressor section of the turbocompressor is in fluid communication with
the portion of the engine requiring the cooling.
In a similar second embodiment of the invention, the first airflow inlet is
in fluid communication with lower temperature fluid (e.g., lower pressure
and temperature discharge air from the booster compressor section of the
engine compressor). The second airflow inlet is in fluid communication
with the outlet of the compressor section of the turbocompressor. The
inlet of the compressor section of the turbocompressor is in fluid
communication with higher temperature air from the engine compressor
(e.g., higher pressure and temperature discharge air from the high
pressure compressor section of the engine compressor). The second airflow
outlet is in fluid communication with the portion of the engine requiring
the cooling.
Several benefits and advantages are derived from the gas turbine engine
cooling system of the invention. Use of the turbocompressor and heat
exchanger of the invention permit higher pressure and lower temperature
air to be used for cooling portions of the engine such as engine hot
section components. Maximum engine thrust, which is especially important
during takeoff and climb, can be increased for a particular redline,
temperature limit for the engine hot section components by using the
higher pressure and lower temperature cooling air of the invention, as can
be appreciated by those skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings illustrate several preferred embodiments of the
present invention wherein:
FIG. 1 is a schematic side view of an aircraft bypass turbofan gas turbine
engine (with the exhaust nozzle omitted for clarity) which employs the
engine cooling system of the invention to cool a high pressure turbine
portion of the engine;
FIG. 2 is a block diagram of a the engine cooling system of FIG. 1
including a turbocompressor and a heat exchanger;
FIG. 3 is a block diagram of an alternate embodiment of the engine cooling
system of FIG. 2;
FIG. 4 is a schematic side view of an aircraft bypass turbofan gas turbine
engine (with the exhaust nozzle omitted for clarity) which employs the
engine cooling system of the invention to cool both a high pressure
turbine portion and a low pressure turbine portion of the engine;
FIG. 5 is a block diagram of a the engine cooling system of FIG. 4
including a turbocompressor and two heat exchangers; and
FIG. 6 is a block diagram of an alternate embodiment of the engine cooling
system of FIG. 5.
In the drawings, like reference numerals designate identical or
corresponding parts throughout the respective figures.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, there is illustrated an aircraft bypass turbofan
gas turbine engine 10 having a generally longitudinally extending axis or
centerline 12 generally extending forward 14 and aft 16. The bypass
turbofan engine 10 includes a core engine (also called a gas generator) 18
which comprises a high pressure compressor or core compressor 20, a
combustor 22, and a high pressure turbine 24, all arranged in a serial,
axial flow relationship. A larger diameter annular drive shaft 26,
disposed coaxially about the centerline 12 of the engine 10, fixedly
interconnects the high pressure compressor 20 and the high pressure
turbine 24.
The core engine 18 is effective for generating combustion gases.
Pressurized air from the high pressure compressor 20 is mixed with fuel in
the combustor 22 and ignited, thereby generating combustion gases. Some
work is extracted from these gases by the high pressure turbine 24 which
drives the high pressure compressor 20. The combustion gases are
discharged from the core engine 18 into a low pressure or power turbine
28. The low pressure turbine 28 is fixedly attached to a smaller diameter
annular drive shaft 30 which is disposed coaxially about the centerline 12
of the engine 10 within the larger diameter annular drive shaft 26. The
smaller diameter annular drive shaft 30 rotates a forward row of fan rotor
blades 32. The smaller diameter annular drive shaft 30 also rotates a low
pressure compressor 34 (also called a booster compressor or simply a
booster). A flow splitter 36, located between the fan blades 32 and the
low pressure compressor 34, separates the air which exits the fan into a
core engine airflow which exits the exhaust nozzle (not shown) and a
surrounding bypass airflow which exits the fan bypass duct 38.
FIG. 1 shows a first application of the engine cooling system 110 of the
invention used for cooling a first portion of the engine 10, wherein the
first portion comprises the high pressure turbine 24. The cooling system
110 receives air: from a duct 112 which bleeds air from the low pressure
compressor discharge region 114; from a duct 116 which bleeds air from the
high pressure compressor discharge region 118; and from a duct 120 which
bleeds air from a region 122 in between such low and high pressure
compressor discharge regions 114 and 118. The cooling system 110
discharges air: to a duct 124 which routes air to the fan bypass duct 38;
and to a duct 126 which routes air to the high pressure turbine 24 region.
FIG. 2 shows a first embodiment 110' of the engine cooling system 110
comprising a turbocompressor 128 and a first heat exchanger 130. The
turbocompressor 128 has a compressor section 132 including an inlet 134
and an outlet 136 and has a turbine section 138 including an inlet 140 and
an outlet 142. Preferably the turbocompressor 128 has air bearings. The
first heat exchanger 130 has an inlet 144 and an outlet 146 for a first
airflow providing cooling to the first heat exchanger 130 and has an inlet
148 and an outlet 150 for a second airflow receiving cooling from the
first heat exchanger 130. The first airflow inlet 144 of the first heat
exchanger 130 is in fluid communication with lower pressure and
temperature air (such as with a portion of the air from the low pressure
compressor discharge region 114 through duct 112/112a as shown in FIGS. 1
and 2). The second airflow inlet 148 of the first heat exchanger 130 is in
fluid communication with higher pressure and temperature air from the
engine compressor (such as with a portion of the air from the high
pressure compressor discharge region 118 through duct 116 as shown in
FIGS. 1 and 2). The first airflow outlet 146 of the first heat exchanger
130 preferably is in fluid communication with the fan bypass duct 38
through duct 124a (and preferably discharges such air into the fan bypass
duct 38 with an aft component of velocity). The second airflow outlet 150
of the first heat exchanger 130 is in fluid communication with the inlet
134 of the compressor section 132 of the turbocompressor 128 through duct
152. The outlet 136 of the compressor section 132 of the turbocompressor
128 is in fluid communication with the high pressure turbine 24 through
duct 126 to cool at least a portion of the high pressure turbine 24. The
inlet 140 of the turbine section 138 of the turbocompressor 128 is in
fluid communication with intermediate pressure and temperature air from
the engine compressor (such as with a portion of the air from the eighth
stage high pressure compressor region 122 through duct 120 as shown in
FIGS. 1 and 2). As can be appreciated by those skilled in the art, the
higher pressure and temperature air has a higher pressure and temperature
than that of the lower pressure and temperature air, and the intermediate
pressure and temperature air has a pressure and temperature intermediate
that of the lower pressure and temperature air and the higher pressure and
temperature air. It is understood that the term "pressure" means total
pressure (i.e., static pressure plus dynamic pressure). The outlet 142 of
the turbine section 138 of the turbocompressor 128 preferably is in fluid
communication with the fan bypass duct 38 through duct 124b (and
preferably discharges such air into the fan bypass duct 38 with an aft
component of velocity).
In an alternate embodiment (not shown), the turbine section 138 of the
turbocompressor 128 has its inlet 140 in fluid communication with the
second airflow outlet 150 of the first heat exchanger 130 instead of being
in fluid communication with the intermediate pressure and temperature air
region 122. This embodiment drives the turbine section 138 of the
turbocompressor 128 with higher pressure air. Preferably, in this
embodiment, the outlet 142 of the turbine section 138 of the
turbocompressor 128 is in fluid communication with the engine low pressure
turbine instead of being in fluid communication (via duct 124b) with the
fan bypass duct 38. This embodiment cools both the high and low pressure
turbines of the engine with the use of a single heat exchanger.
FIG. 3 shows a second embodiment 110" of the engine cooling system 110
which is identical to the first embodiment 110' of FIG. 2 previously
discussed, but with three differences. First, the second airflow outlet
150 of the first heat exchanger 130 is in fluid communication with the
high pressure turbine 24 through duct 126 to cool at least a portion of
the high pressure turbine 24. Second, the inlet 134 of the compressor
section 132 of the turbocompressor 128 is in fluid communication with
higher pressure and temperature air from the engine compressor (such as
with a portion of the air from the high pressure compressor discharge
region 118 through duct 116 as shown in FIGS. 1 and 3). Third, the outlet
136 of the compressor section 132 of the turbocompressor 128 is in fluid
communication with the second airflow inlet 148 of the first heat
exchanger 130.
FIG. 4 shows a second application of the engine cooling system 210 of the
invention used for cooling a first portion of the engine 10, wherein the
first portion comprises the high pressure turbine 24 and also for cooling
a second portion of the engine 10, wherein the second portion comprises
the low pressure turbine 28. The cooling system 210 as shown in FIG. 4 is
identical to the first application's cooling system 110, as shown in FIG.
1, but with one addition. The cooling system 210 also discharges air to a
duct 154 which routes air to the low pressure turbine 28 region.
FIG. 5 shows a first embodiment 210' of the engine cooling system 210 which
is identical to the first embodiment 110' of the engine cooling system 110
of FIG. 2 previously discussed, but with one addition and one difference.
Briefly, the addition is a second heat exchanger 156, and the difference
is in the duct which is in fluid communication with the outlet 142 of the
turbine section 138 of the turbocompressor 128. More particularly, the
second heat exchanger 156 has an inlet 158 and an outlet 160 for a third
airflow providing cooling to the second heat exchanger 156 and has an
inlet 162 and an outlet 164 for a fourth airflow receiving cooling from
the second heat exchanger 156. The first airflow inlet 158 of the second
heat exchanger 156 is in fluid communication with lower pressure and
temperature air (such as with a portion of the air from the low pressure
compressor discharge region 114 through duct 112/112b as shown in FIGS. 4
and 5). The second airflow inlet 162 of the second heat exchanger 156 is
in fluid communication with the outlet 142 of the turbine section 138 of
the turbocompressor 128 through duct 166. The first airflow outlet 160 of
the second heat exchanger 156 preferably is in fluid communication with
the fan bypass duct 38 through duct 124c (and preferably discharges such
air into the fan bypass duct 38 with an aft component of velocity). The
second airflow outlet 164 of the second heat exchanger 156 is in fluid
communication with the low pressure turbine 28 through duct 154 to cool at
least a portion of the low pressure turbine 28.
FIG. 6 shows a second embodiment 210" of the engine cooling system 210
which is identical to the second embodiment 110" of FIG. 3, but with the
one addition (the second heat exchanger 156) and the one difference (the
duct which provides fluid communication from the outlet 142 of the turbine
section 138 of the turbocompressor 128) as previously discussed.
Conventional engine cooling techniques duct compressor air directly to the
high pressure turbine 24 region and the low pressure turbine 28 region of
the engine 10. The cooling system of the invention can be used to augment
such conventional engine cooling techniques or it can be used to
substitute for such conventional techniques.
The operation of the first embodiment 210' of the engine cooling system 210
is typical of the other embodiments, and will be described with reference
to a numerical example based on engineering analysis where the pressure P
is measured in psia and the temperature T is measured in degrees R.
Referring to FIGS. 4 and 5, it is seen that air (P=34.8, T=810) from the
low pressure compressor discharge region 114 is carried by duct 112a to
the first heat exchanger 130 to cool air (P=497, T=1689) from the high
pressure compressor discharge region 118 carried by duct 116 entering the
first heat exchanger 130 so that the airflow receiving cooling will exit
the first heat exchanger 130 as air (P=462, T=1369) carried by duct 152 to
the compressor section 132 of the turbocompressor 128. The compressor
section 132 is driven by the turbine section 138 from air (P=277, T=1486)
from the intermediate compressor region 122 carried by duct 120. Air
(P=497, T=1416) leaves the compressor section 132 of the turbocompressor
128 in duct 126 to cool the high pressure turbine 24. (Conventional
cooling of the high pressure turbine directly with air from the high
pressure compressor discharge region would deliver such air at P=464 and
T=1647.) In a similar fashion, air (P=140, T=1109) leaves the second heat
exchanger 156 in duct 154 to cool the low pressure turbine 28.
(Conventional cooling of the low pressure turbine directly with air from
the intermediate compressor region would deliver such air at P=130 and
T=1186.) The greater engine cooling capacity of the system of the
invention achieves a net thrust of 51878 pounds compared with 45139 pounds
of net thrust using conventional cooling (with the high temperature
turbine blade temperature at a "redline" limit of 1838 for both the
cooling system of the invention and the conventional cooling). The
improvement in net thrust for the engine cooling system of the invention
is nearly fifteen percent.
The foregoing description of a preferred embodiment of the invention has
been presented for purposes of illustration. It is not intended to be
exhaustive or to limit the invention to the precise form disclosed, and
obviously many modifications and variations are possible in light of the
above teachings. For example, it is understood that the phrase "engine
compressor" includes any low, intermediate, and/or high pressure engine
compressor. Also, various portions of the engine which may be cooled by
the engine cooling system of the invention include those portions
involving high pressure turbine cooling, low pressure turbine cooling,
combustor cooling, compressor disc cooling, compressor discharge cooling,
compressor and turbine case cooling, clearance control cooling, etc.
Additionally, lower pressure and temperature air may be bled or ducted
from the fan region, the fan bypass region, etc. as well as from the low
pressure compressor region. Further, the invention is applicable to gas
turbine engines having axial, radial, or other types of gas turbine engine
compressors and/or turbines. It is likewise understood that in some
applications, the engine cooling system of the invention may employ valves
to control the airflow in the various ducts, and/or the engine cooling
system of the invention may be employed in those engines having variable
turbine nozzles where greater cooling is required when the turbine nozzle
area is reduced. It is noted that the first airflow can be generalized as
a first fluid flow having a higher temperature than that of the second
airflow, and that such first fluid flow can be engine fuel wherein, for
example, duct 112 would convey some fuel from the fuel tank to the heat
exchanger(s) and duct 124 would convey the fuel from the heat exchanger(s)
back to the fuel tank or to the combustor, etc. (such arrangement not
shown in the drawings). Such modifications and variations, and other
modifications and variations, are all within the scope of the claims
appended hereto.
Top